My brother just charged his friend ${S} for offering a bet: if the temperature of tomorrow is above 70, my brother will pay 1.5 times ${S} to his friend; if the temperature is below 70 tomorrow, my brother will pay 0.5 times ${S} to his friend. I do not want my brother to lose money when tomorrow's temperature is above 70 and decide to buy an insurance that will make my brother break even when tomorrow's temperature is above 70 (in other words, the insurance policy will pay my brother 0.5 times ${S} when tomorrow's temperature is above 70). If risk free rate is zero, how much should I pay for this insurance (keep two decimal places)?